News of the missing boat comes amid criticism of the European Union's lack of rescue missions in the Mediterranean Sea.
The testimony of the 79 people rescued by the Aita Mari match with those of human rights organisations working in Libya: detention centres are places for torture and extortion. "You get arrested just because you are black," Ismail explained.
The 47-year old woman was floating in a rubber dinghy in the Aegean Sea for nearly two days before she was rescued by Greek coast guards.
"We are extremely relieved to finally bring the remaining 88 exhausted and traumatised rescued persons to a safe port soon," said German NGO Sea-Eye.
The situation aboard Ocean Viking puts EU's new plan to distribute migrants to the test.
The migrants were picked up in two separate operations off the coast of Libya, MSF, who runs the ship alongside SOS Mediterranee, said on Twitter.
Charity ship Ocean Viking rescued 50 migrants from the Mediterranean on Sunday.
Almost 100 migrants from Spanish charity ship Open Arms finally disembarked on the Italian island of Lampedusa after nearly three weeks at sea.
An Italian prosecutor ordered the seizure of the Open Arms ship, stranded off the Italian island of Lampedusa with almost 100 migrants aboard, just hours after the Spanish government said it would send a navy ship to escort the vessel back to Spain.
"Ocean Viking", operated by Doctors Without Borders (MSF) and SOS Méditerranée, is stranded off the coast of Libya with around 356 migrants.
More than 500 rescued migrants on two NGO ships remain stranded